The present invention relates to the corrosion testing art. It finds particular application in conjunction with accelerated corrosion testing chambers and will be described with particular reference thereto. However, it should be appreciated that the present invention also finds application in conjunction with other types of environmental testing systems and applications which require control or regulation of relative humidity.
Corrosion testing is required of many items which must meet corrosion resistance standards set by various governmental agencies and industrial concerns. The testing of the ability of various products to withstand corrosive influences is frequently conducted by accelerated exposure techniques. The methods utilize a test cabinet into which parts to be tested are placed. A corrosive atmosphere or environment is then introduced into the cabinet at specified levels for specified periods of time. Exposed items are then removed from the cabinet and scrutinized for signs of corrosion, structural breakdown and the like. The corrosion test cabinets must be capable of maintaining rigid standards and capable of repetition under identical conditions.
Present corrosion resistance standards, such as the proposed SAE (Society of Automotive Engineers) J2334 standard or the General Motors 9540-P standard, specify that parts or items to be tested must be exposed to a number of different corrosive influences in specified amounts for specified periods of time. In particular, parts to be tested must be exposed to a number of salt spray (fog) cycles, humidity cycles and drying cycles. However, known corrosive testing cabinets do not have the capability to deliver multiple corrosive influences to the parts to be tested within a single testing chamber.
In particular, known corrosive salt spray (fog) testing chambers can not regulate, control or maintain specified levels of relative humidity within a testing chamber during humidity and drying cycles as required by present corrosion resistance standards. Thus, to comply with present corrosion resistance standards, it has been necessary to move the parts to be tested from one corrosion testing cabinet to another when the testing cycle (i.e. the type of corrosive influence) changes.
Accordingly, it has been considered desirable to develop a new and improved corrosion testing chamber which meets the above-stated needs and overcomes the foregoing difficulties and others while providing better and more advantageous results.